FIELD OF THE INVENTION
This invention relates to improvements in taps, and more particularly, taps of the type where only part of a full rotation of the tap spindle is necessary to facilitate full opening of the tap from a closed condition, usually a quarter or 90.degree. turn, although the present invention is not restricted to application to such taps and includes 180.degree. turn taps.
In some taps of the quarter turn type referred to above, an arrangement of discs, usually of ceramics, incorporating apertures therethrough has been proposed. Adjacent faces of the discs are mounted to abut each other such that rotation of one of the discs relative to the other brings the apertures through the respective discs into and out of alignment to allow operation of the tap between fully opened and fully closed conditions with only a part turn of the tap spindle, namely through 90.degree. (quarter turn). A tap of the above general type is disclosed in the specification of Australian Pat. No. 526,072.
In order to meet the standards set down by water supply authorities, including Australian water supply authorities, and with which taps must comply, the distance between the outer surface surrounding the access opening to the interior of a tap body within which a tap top assembly is to be inserted, to the valve seat within the body, has a specified value within specified tolerances, and thus, as the inner end of the assembly is required to permanently seat in sealing engagement with the valve seat within the tap body, the corresponding length of the tap top assembly must comply with the specified distance. However, the allowable tolerances can lead to a situation where the relevant length of the tap top assembly may be less than the specified distance for the tap body thus preventing proper sealing engagement with the valve seat in the tap body, or if longer, preventing proper sealing of the tap top assembly with the tap body around the access opening within which the assembly is received.
It is also desirable that tap top assemblies be provided as replacements for tap top assemblies in existing tap bodies so as to enable conversion of an existing tap to a quarter turn tap, and thus the relevant dimensions may not be such as to ensure proper sealing engagement of the tap top assembly in the existing tap body.